package com.ihr360.job.core.scope;

import com.ihr360.job.core.config.support.BatchPropertyContext;
import com.ihr360.job.core.entity.JobExecution;
import com.ihr360.job.core.scope.context.JobContext;


/**
 * Central convenience class for framework use in managing the job scope
 * context. Generally only to be used by implementations of {@link Job}. N.B.
 * it is the responsibility of every {@link Job} implementation to ensure that
 * a {@link JobContext} is available on every thread that might be involved in
 * a job execution, including worker threads from a pool.
 *
 * @author Dave Syer
 * @author Jimmy Praet
 * @since 3.0
 */
public class JobSynchronizationManager {
    private static final SynchronizationManagerSupport<JobExecution, JobContext> manager = new SynchronizationManagerSupport<JobExecution, JobContext>() {

        @Override
        protected JobContext createNewContext(JobExecution execution, BatchPropertyContext args) {
            return new JobContext(execution);
        }

        @Override
        protected void close(JobContext context) {
            context.close();
        }
    };

    /**
     * Getter for the current context if there is one, otherwise returns null.
     *
     * @return the current {@link JobContext} or null if there is none (if one
     * has not been registered for this thread).
     */
    public static JobContext getContext() {
        return manager.getContext();
    }

    /**
     * Register a context with the current thread - always put a matching
     * {@link #close()} call in a finally block to ensure that the correct
     * context is available in the enclosing block.
     *
     * @param JobExecution the step context to register
     * @return a new {@link JobContext} or the current one if it has the same
     * {@link JobExecution}
     */
    public static JobContext register(JobExecution JobExecution) {
        return manager.register(JobExecution);
    }

    /**
     * Method for unregistering the current context - should always and only be
     * used by in conjunction with a matching {@link #register(JobExecution)}
     * to ensure that {@link #getContext()} always returns the correct value.
     * Does not call {@link JobContext#close()} - that is left up to the caller
     * because he has a reference to the context (having registered it) and only
     * he has knowledge of when the step actually ended.
     */
    public static void close() {
        manager.close();
    }

    /**
     * A convenient "deep" close operation. Call this instead of
     * {@link #close()} if the step execution for the current context is ending.
     * Delegates to {@link JobContext#close()} and then ensures that
     * {@link #close()} is also called in a finally block.
     */
    public static void release() {
        manager.release();
    }
}